Republican Cast of Characters Are Sorting Themselves Into a Matrix of Categories

This Labor Day week marks the official start of the 2014 general-election season, so what's the logical thing to do? Look forward to the 2016 presidential election, of course.

OK, so that isn't entirely logical. But there is no doubt that the 2016 presidential race—which figures to be as wide open, unpredictable and flat-out interesting as any in memory—will be providing much of the background music for this year's congressional...